Emergency mechanism for prime movers.



W. L. R. EMMET.

EMERGENCY MECHANISM EOE PRIME MovEEs.

APPLICATION FILED NOV. 2Q, 1913.

Patented May 5, 1914.

Inventor? William LREmmeb b9 I v aqttg.

E EdJ UNITED STATES PATENT OFFICE.

WILLIAM L.

R. manna, or SCHENECTADY, NEW YORK, assmnon TO GENERAL ELECTRIC COMPANY,'A CORPORATION on NEW YORK.

EMERGENCY MECHANISM FOR PRIME MOVERS.

To all whom it may concern:

Be it known that I, WILLIAM L. R. EM- Mn'r, a citizen of the United States, residing at Schenectady county of Schenectady, State of New ork, haveinvented certain new and useful Improvements in Emergency Mechanism for Prime Movers, of which the following is a specification.

The resent invention is a continuation .in part 0 my pending application Serial No. 508,942, filedJuly 22, 1909, relating to ship propulsion.

Briefly stated, the parent application discloses a twin screw system of ship propulsion wherein highand low-pressure turbines are provided for each screw and also an electric generator and motor. For driving the ship at full speed all of said apparatus is utilized,

while for cruising speeds the high-pressure turbines are operated as condensing units and the current from their generators utilized to drive motors On the propeller shafts, said low-pressure turbines either being disconnected from said shafts or running idle vention to safeguard said system ing overning mechanism that is normally in a vacuum to reduce rotation losses.

In such a system ofship propulsion conditions may arise due to various causes, resulting in over-speeding of either the high or low-p pressure turbine or both, of either or both screws, and it-is the object of the present in- I y providinactive and which comesinto service when said over-speed takes placle and acts to out ofl' the supply of steam to said turbines.

For a consideration of what I believe to be novel and my invention, attention is dirooted to the accompanying,description' and claims appended thereto. I

In the accompanying drawing, which illustrates one of the embodiments of my in vention, Figure 1 is a plan view illustrating myjimprovement as applied to a system of ship propulsion, and Fig. 2 is a detail view of the emergency mechanism for shutting down the system when either the high-pressure turbine or, the low-pressure turbine exceeds a predetermined maximum speed.

I may utilize my invention in a ship having a single screw or propeller or in one having a reater number. For the purpose of simpli yin the illustration I have shown only one-'hal of a twin screw arrangement, the other half bein a duplicate.

3 indicates a hig -pr essure high-speed tur- Speciflcation of Letters Patent.

Patented May 5,1914.

7 I Application filed November 20, 1913. Serial N 0. 802,145.

bine which drives a three-phase alternating current generator 4. The rotors of the turbine and generator are mounted on the shaft 5. This shaft is entirely independent of the pipe 6, and the exhaust therefrom passes by the conduit 7 directly to the condenser 8 under certain conditions and under other conditions by the pipe 9 to the low-pressure low-speed turbine 10- In the pipe 9 is a relief valve 11- which automatically opens in response to a predetermined increase in pressure and discharges steam from the highpressure turbine to the low-pressure turbine. In the pipe 6 is provided a hand-actuated shut-off valve 12 and also a combined emerency and throttle valve 13 which is closed in response to excess speed conditions, as will be referred to later. The admission of steam to the high-pressure turbine is controlled by a p urality of hand-actuated valves 14, the latter serving to open and closenozzles or fluid passages leading to the rotor of the turbine. The low-pressure turbine is-. permanently connected to the condenser-by the conduit 15. The'rotor of the low-pressure turbine is mounted on the shaft.

16 which forms a continuation of the ropeller shaft 17 Between the propellers aft and the" turbine shaft is a releasable coupling 18 of anysuitable construction. Mounted on the propeller shaft is the rotor 19' of an induction motor, the field or stationary part 20 bein mounted on a suitable support. On the le t-hand end of the shaft 17 is a screw Or propeller 21 of suitable size,

shape and pitch. Current from the generator 4 is supplied to the induction motor by theconductors or bus-bars'22, and a switch 23 is provided by means of which the generator and motor may be connected and'disconnected. In circuit with the motor is a pole changing device or switch 24 by means of which the number of field poles of the motor can be changed and therefore the fixed speed relation between the generator and motor changed.

In order to reverse the direction of the movement ofthe ship the high-pressure turbine may be provided with a. reversing element comprising the usual nozzles and stationary buckets and also rotating buckets mounted on the shaft thereof and supplied with steam by the pipe 25 communicating with the boiler. In this pipe is athrottle valve 26. The supply of steam to the reversing element is directly controlled by the hand valves 27 which serve to out nozzles or passages leading to the rotor into and out of service. i

For cruising speeds steam enters the highpressure turbine and passes by the conduit 7 -.to the condenser. Under these conditions no steam will pass through the conduit 9 and hence the low-pressure turbine will not be in operation. Current from the generator is 1 5 Supplied to the motor andthe latter drives the ropeller shaft. Under these conditions the ow-pressure low-speed turbine may remain coupled to the propeller shaft or it may be disconnected by releasing the parts of the coupling 18'.

1 the casing of the low-pressure turbine is connected to the'condenser, the rotation losses will be small and it will, therefore, be undesirable in. many cases to open the cou- 26 pling 18. 3

i Assuming that it is desired to drive the vessel at maximum speed, steam is admitted to the high-pressure turbine, and by suitable valve mechanism (not shown) located With- 89 in its casing the low-pressure portion of the turbine 3 is cut off. This results in building up'su'ch a pressure in the turbine casing and in the pipe 9 as to cause the relief valve 11 to'automatically open and discharge steam into the low-pressure turbine 10.

Under these conditions both turbines and also the generator and motor will participate in the propulsion of the vessel. When the low-pressure portion of the high-pressure 4 turbine is shut off the rotation losses of the I idlebuckets will be small, because they are sub'ectedto the effects of the condenser.

Vihen the vessel .is underway it may happen, due to various causes, that the speed of 4 the rotor of the high-pressure orthe low- "pressure turbine may exceed that which is 'regarded as safe and desirable. As an illustration of the causes of over-speeding, the circuit between-the' generator and the motor may-be interrupted thus taking all the load off Ofythfi generator, or the propeller or its shaft may brealrand thus relieve the generator of all or the greater portion of its load. In the event that the low-pressure turbine had been disconnected from the propeller shaft by opening the coupling 18 any substantial leakage of steam through the relief valve. llwould cause the rotor of said turbine to overspeed. If the low-pressure turbine was assisting to drive the propeller and the coupling 18 broke or was accidentally released its rotor would overspeed. To prevent such over-speeding Imount on the shaft of the high-speed turbo-generator an emergency speed governor 30 and on the Owing to the fact that.

low-pressure turbine shaft' an emergency speed governor 31. These governors may be of any suitable construction. As shown, 4 each comprises a ring- 32 so arranged that its periphery is normally concentric to the axis of the shaft, although its mass is unsymmetrically arranged with respect to said axis. As the speed increases abnormally, say by 10% for example, the ring moves laterally with respect to the shaft axis against 7 the action of a spring 34 and engages the lever 35 causing one end thereof to bridge the contacts 36 and 37 adjacent thereto and close the circuit of a solenoid magnet 38 mounted on a bracket 39 carried by the casing of the valve 13. The core of this mag- I net when energized pulls the detent 40 out of the notch of the sliding nut 41 of the emergency valve 13, thereby permitting the valve to close, due to its unbalanced relation, said 35 nut sliding downward with it. This unbalanced relation is obtained by enlarging the stem 42 and exposing its lower end to atmosphere. To reset the valve after an emergency operation the hand wheel is first rotated in the valve closing direction and, the

valve being on itsseat, the nut is free to move upwardly on the stem to the position shown, after which the detent 4:0 is moved in the position shown either automatically or by hand. After the nut is locked the valve can be manipulated by the hand wheel, the same as any other nut and screw valve, The emergency governor for the low-pres sure low-speed turbine is similar in construction to the oneabove described and operates in the same manner to close the circuit of the said solenoid magnet 38. Current for this purpose is supplied by a suitable source, such for example, as a battery, -or the circuits 43 of the exciter of the alternating current generator 4. -As before stated the highpressure turbine operates at a higher speed than the low-pressure turbine. This means that the governors 30 and'31 will be set to operate at different speeds, that of the former being higher than the latter. This can readily be done by properly distributing the mass of the metal in therings or by changing the tension of the adjusting or opposing springs 34, or by changing both the distribution and the spring tension.

I have illustrated electrical means for transmitting movements of both of the speed governors to the valve tripping mechanism, but it is to be understood other means for transmitting these mot-ions may be em-' ployed, the principal thing being to insure certainty of operation ofthe emergency valve when the speed of either of the shafts in-: creases above the predetermined desired maximum.

From the foregoing it will be Seen that provision is madefor shutting down the;

system whenever one of the parts exceeds its predetermined maximum speed. It may happen that the low-pressure turbine overspeeds or the high-pressure turbine, in both cases the final result is the same; i. e., closing the combined emergency and throttle valve in the pipe conveying high-pressure steam from the boiler to the turbine 3.

I have not illustrated an emergency valve in the supply pipe 25 leading to the reversing element in the high-pressure turbine since ordinarily the turbine is driven in the reverse direction for short periods only and the engineer will usually be stationed at the valve during such times, and hence a governor is unnecessary. I can, however, 10- cate an emergencyvalve, such as 13, in the pipe 25 and control it by the speed governors 30 and 31 as herein indicated.

In a twin screw arrangement the parts are duplicated for the other propelling mechanism, and if desired the circuits from each governor may be arranged in parallel and extend to both emergency valves so that bothwill close if any turbine in the system overspeeds as will be readily understood.

I have illustrated a type of emergency governor that is well adapted for the purposes herein set forth, but it is to be understood that my invention is not limited to the specific embodiment illustrated. One feature that makes the governor disclosed desirable for this purpose is, that it is operative whichever way its shaft rotates.

In accordance'with the provisions of the patentstatutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. In combination, prime movers arranged to drive a common load, conduit means supplying motive fluid thereto, emergency valve means in said conduit means, and an emergency governor means for each of said prime movers which causes said valve means to shut. when saidv prime movers over-speed.

2. In combination, individual prime movers, one of which receives and is driven by the exhaust of the other, a conduit supplying motive fluid to the prime mover of higher pressure, an emergency valve in said conduit, an emergency governor for each of said prime movers and is sensitive to overspeeding thereof, and means for causing either of said governors to trip the emer gency valve.

3. In combination, individual prime movers operating under different pressure conditions and at different speeds, the prime mover of lower pressure receiving the exhaust from the prime mover of higher pressure, emergency governors therefor which are set to operate at different speeds, a'con-- duit admitting motive fluid to the prime mover of higher pressure, and means for causing said governors to trip the valve when overspceding of either prime mover occurs.

4. In combination, a high-pressure engine,

a low-pressure turbine receiving exhaust therefrom and rotating at a different speed, a valve controlling the admission of motive fluid to the engine, and governor means responsive to an abnormal speed of the engine and of the low-pressure turbine for closing said valve.

5. In combination, high and low-pressure prime movers rotating at different speeds, the latter receiving and being driven by the exhaust from the former, means for transmitting the power developed by the prime mover to an energy consuming device which is common thereto, a valve in the inlet of the high-pressure prime mover, an emergency governor for each of the prime movers, and means controlled by said governors for closing said valve. and shutting down both prime movers.

6. In combination, a shaft, a high-pressure high-speed turbine, a valve controlling the supply of steam to said turbine. a lowpressure low-speed turbine connected to the first turbine so as to' receive exhaust therefrom, means for transmitting the power de veloped by the turbines to said shaft, means for regulating the supply of exhaust to the low-pressure turbine, an emergency governor for each turbine, and connections from the governors to said valve for shutting off the steamsupply when the speed of either turbine exceeds a predetermined limit.

In witness whereof, I have hereunto set my hand this 18th day of November, 1913.

VVILLIAM L. R. EMMET.v Witnesses:

EDWIN V. NoxoN, BENJAMIN B. HULL. 

